Various devices have been developed to detect the flow of fluids such as water. For example, devices have been developed to detect leaks in fluid carrying conduits and have been developed to monitor the level of fluids in tanks for storing fluids. For example, U.S. Pat. No. 4,355,654 to Levesque et al. discloses a device for monitoring the flow of fluid through a pair of conduits. The normal flow of fluid through the conduits is monitored, and the device blocks the flow of fluid through one conduit when leakage of fluid from the conduit is detected. The apparatus is particularly designed for dual control systems and only blocks the flow of fluid through one conduit so that the entire fluid system is not shut down. If both conduits are simultaneously damaged, the apparatus diverts all fluid to the less severely damaged conduit.
Other devices have been developed to detect fluid flow through a conduit. In U.S. Pat. No. 4,252,088 to Frisby, leaks in a fluid system are detected by magnetic switches engaged with a flapper which is displaced by movement of the fluid through the system. A thermal time delay switch prevents actuation of the magnetic switches due to slight variations in the fluid pressure. In U.S. Pat. No. 4,522,229 to Van de Moortele, an elaborate system of chambers and valves are arranged to stop the flow of the fluid when a leak in the fluid system is detected. Since slow leaks and catastrophic fluid leaks are detected with a combination of fluids in chambers, the device only works when it is oriented in a fixed orientation. This requirement limits the design flexibility of the apparatus and may render the apparatus useless in a moving environment.
None of these devices provide a comprehensive solution to the problem of detecting abnormal fluid flow to an appliance such as a toilet. In an appliance, as in certain industrial uses, the normal flow of fluid through a conduit may be intermittent and failure of the fluid carrying system can occur in different ways. For example, failure of the ballcock in a toilet tank may result in a rapid loss of water. If the stopper in the bottom of the tank leaks, slow and intermittent fluid flow may result in a significant water loss over a period of time. Detection of a rapid loss of water, or of an intermittent flow, is difficult since water normally flows through the conduit in an intermittent fashion. If the abnormal fluid flow is not quickly detected, a significant amount of fluid can be lost before the leak is identified and corrected.
Accordingly, a need exists for a fluid control apparatus which detects unusual flow of a fluid through a conduit and selectively prevents the flow of fluid through the conduit after the abnormal flow is detected.